Myth: Polygraph tests are completely reliable

Truth and Lies

Can you find the lies?

Another myth roaming around out there is that a polygraph, or lie detector, test is a completely accurate way to detect if someone is dishonest. Although the data from a polygraph test can shed light on some truth and does prove itself to be useful, it has it’s faults. Its not 100% accurate; all possibilities should be taken into account. There are some factors you need to consider that may alter the results:

1. For starters, the whole concept of a polygraph test is to measure the blood pressure, pulse, respiration and skin conductivity while the subject is asked a series of questions. If you are able to control or mask your reactions at key moments of the tests you may be able to throw the results off enough to have an inconclusive result.

An underlying problem is theoretical: There is no evidence that any pattern of physiological reactions is unique to deception. An honest person may be nervous when answering truthfully and a dishonest person may be non-anxious. (APA)

2. Take another perspective: It could be that the very presence of this lie-detector machine tricks people into being more honest.

A particular problem is that polygraph research has not separated placebo-like effects (the subject’s belief in the efficacy of the procedure) from the actual relationship between deception and their physiological responses. One reason that polygraph tests may appear to be accurate is that subjects who believe that the test works and that they can be detected may confess or will be very anxious when questioned. If this view is correct, the lie detector might be better called a fear detector. (APA)

person strapped to lie detector machine

Lie detector test in process

3. Take a look at Aldrich Ames, who was part of the Soviet counter-espionage program for the CIA but was actually a Soviet spy. When the CIA started to realize there was was a mole in the agency, it took them a little while to hone in on Ames. Eventually, they put him through a polygraph test where his answers were deceptive, but passed…twice!

Ames was initially “terrified” at the prospect of taking the test, but he was advised by the KGB “to just relax”….[he] received the simple instruction to: “Get a good night’s sleep, and rest, and go into the test rested and relaxed. Be nice to the polygraph examiner, develop a rapport, and be cooperative and try to maintain your calm.Additionally, Ames said, “`There’s no special magic…Confidence is what does it. Confidence and a friendly relationship with the examiner… rapport, where you smile and you make him think that you like him.  (Wikipedia)

The National Academy of Sciences conducted a study in 2003 where they examined 57 polygraph studies.

In populations of examinees such as those represented in the polygraph research literature, untrained in countermeasures, specific-incident polygraph tests can discriminate lying from truth telling at rates well above chance, though well below perfection….polygraph tests had too high a margin of error to be genuinely informative. (The Straight Dope)

All in all, the polygraph test is not perfect, it has its pitfalls. People have deceived their way to a passing grade. Although it has proved is use over the years, it’s not something we should rely on…yet. Technology is growing everyday- who knows what the future polygraph tests will have in store!


Posted on October 19, 2013, in Myths. Bookmark the permalink. Leave a comment.

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